Method and apparatus for transmitting and receiving periodic channel information in wireless communication system

ABSTRACT

A method and apparatus in which a terminal transmits channel information for at least one serving cell to a base station in a wireless communication system is provided. The method for receiving periodic channel information by a base station in a wireless communication system includes determining whether to set a Physical Uplink Shared CHannel (PUSCH) mode for allowing a terminal to periodically transmit a plurality of channel information to the base station in one sub-frame, transmitting PUSCH mode information including a result of the determination to the terminal, and receiving the plurality of channel information from the terminal using a PUSCH in the one sub-frame, according to the result of the determination.

PRIORITY

This application is a continuation application of U.S. patentapplication Ser. No. 13/722,009 filed on Dec. 20, 2012, which claimspriority under 35 U.S.C. §119(a) to a Korean Patent Application filed inthe Korean Intellectual Property Office on Dec. 20, 2011 and assignedSerial No. 10-2011-0138310, the entire disclosure of which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method and apparatus in which aterminal transmits channel information for at least one serving cell toa base station in a wireless communication system, and moreparticularly, to a method and apparatus for transmitting and receivingperiodic channel information in a wireless communication system.

2. Description of the Related Art

Generally, mobile communication systems have been developed to providevoice services, to allow for mobility of a user. Mobile communicationsystems have expanded data services as well as voice services, and now,they are capable of providing high-speed data services. However, inmobile communication systems which currently provide services, due to ashortage of resources and user's demands for higher-speed services,mobile communication systems are required which are further developed.

To meet such demands, standardization work on Long Term Evolution (LTE),one of the next-generation mobile communication systems, is in progressin the 3^(rd) Generation Partnership Project (3GPP). LTE implementshigh-speed packet-based communication at a data rate of up to about 100Mbps. To this end, various schemes have been discussed, such as a schemefor reducing the number of nodes located on a communication path bysimplifying a structure of a network and a scheme for arranging wirelessprotocols close to wireless channels.

In 3GPP LTE release-10 (rel-10), to support higher data transmissionquantity than LTE rel-8, a bandwidth extension technique has beenadopted. Bandwidth extension, also called Carrier Aggregation (CA), mayextend a band, thus increasing data transmission quantity by theextended band when compared to an LTE rel-8 terminal for transmittingdata in a band. Each band is called a Component Carrier (CC), and theLTE rel-8 terminal is prescribed to have one CC for each of a Downlink(DL) and an Uplink (UL). UL CCs, which are SIB-2 connected with DL CCs,are called a cell. The SIB-2 connection relationship between the UL CCsand the DL CCs is transmitted as a terminal-dedicated signal. A terminalwhich supports CA may receive DL data and transmit UL data throughmultiple serving cells.

When a base station has difficulty in sending a Physical DownlinkControl CHannel (PDCCH) to a particular terminal in a particular servingcell in LTE rel-10, it transmits the PDCCH to the terminal in anotherserving cell and sets a Carrier Indicator Field (CIF) as a field forindicating that the PDCCH indicates a Physical Downlink Shared CHannel(PDSCH) or a Physical Uplink Shared CHannel (PUSCH) of the anotherserving cell. The CIF may be set in the terminal which supports CA. TheCIF is determined to indicate the another serving cell by adding 3 bitsto the PDCCH information in the particular serving cell. The CIF isincluded only when cross carrier scheduling is performed. If the CIF isnot included, cross carrier scheduling is not performed. When the CIF isincluded in a DL assignment, the CIF indicates a serving cell in whichthe PDSCH scheduled by the DL assignment is to be transmitted. If theCIF is included in a UL grant, the CIF is defined to indicate a servingcell in which the PUSCH scheduled by the UL grant is to be transmitted.

As such, in LTE rel-10, the bandwidth extension technique CA is defined,such that multiple serving cells may be set in a terminal. For datascheduling of the base station, the terminal periodically oraperiodically transmits channel information for the multiple servingcells to the base station.

In LTE rel-11, a maximum of five serving cell setting scenarios areassumed, and in this case, channel information transmission for multipleserving cells in one sub-frame may collide with each other. Thus, a needexists for a method for supporting an operation of the terminal suchthat channel information for as many serving cells as possible may beperiodically transmitted in one sub-frame.

SUMMARY OF THE INVENTION

Accordingly, the present invention is provided to address at least theabove-described problems and provide at least the advantages describedbelow.

Accordingly, the present invention provides a method and apparatus fortransmitting channel information for multiple serving cells at aterminal in a wireless communication system, without wastingtransmission resources of a DL control channel.

The present invention also provides a method and apparatus forincreasing a transmission quantity by receiving channel informationperiodically transmitted from a terminal and performing optimalscheduling for serving cells.

According to an aspect of the present invention, there is provided amethod for receiving periodic channel information by a base station in awireless communication system, the method including determining whetherto set a Physical Uplink Shared CHannel (PUSCH) mode for allowing aterminal to periodically transmit a plurality of channel information tothe base station in one sub-frame, transmitting PUSCH mode informationincluding a result of the determination to the terminal, and receivingthe plurality of channel information from the terminal using a PUSCH inthe one sub-frame, according to the result of the determination.

According to another aspect of the present invention, there is provideda method for transmitting periodic channel information by a terminal ina wireless communication system, the method including receiving PhysicalUplink Shared CHannel (PUSCH) mode information from a base station,determining based on the PUSCH mode information whether a PUSCH mode isset to periodically transmit a plurality of channel information to thebase station in one sub-frame, and transmitting the plurality of channelinformation to the base station using a PUSCH in the one sub-frame,according to a result of the determination.

According to another aspect of the present invention, there is provideda base station in a wireless communication system, the base stationincluding a controller for determining whether to set a Physical UplinkShared CHannel (PUSCH) mode for allowing a terminal to periodicallytransmit a plurality of channel information to the base station in onesub-frame, a transmitter for transmitting PUSCH mode informationincluding a result of the determination to the terminal, and a receiverfor receiving the plurality of channel information from the terminalusing a PUSCH in the one sub-frame, according to the result of thedetermination.

According to another aspect of the present invention, there is provideda terminal in a wireless communication system, the terminal including areceiver for receiving Physical Uplink Shared CHannel (PUSCH) modeinformation from a base station, a controller for determining based onthe PUSCH mode information whether a PUSCH mode is set to periodicallytransmit a plurality of channel information to the base station in onesub-frame, and a transmitter for transmitting the plurality of channelinformation to the base station using a PUSCH in the one sub-frame,according to a result of the determination.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of embodiments of thepresent invention will be more apparent from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a flowchart illustrating a process of requesting andtransmitting aperiodic channel information in LTE rel-10;

FIG. 2 is a flowchart illustrating a process of setting an UplinkControl Information (UCI) PUSCH transmission mode and receiving a UCIPUSCH to transmit channel information for multiple serving cells at abase station according to the present invention;

FIG. 3 is a flowchart illustrating a process of transmitting channelinformation for multiple serving cells through a UCI PUSCH at a terminalaccording to the present invention;

FIG. 4 is a block diagram illustrating a base station according to thepresent invention;

FIG. 5 is a block diagram illustrating a terminal according to thepresent invention; and

FIG. 6 is a flowchart illustrating a method according to the presentinvention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

Embodiments of the present invention will now be described in detailwith reference to the annexed drawings. It should be noted thatthroughout the drawings, like reference numerals refer to likecomponents. In the following description, known functions andconfigurations will not be described in detail if they unnecessarilyobscure the subject matter of the present invention.

When an embodiment of the present invention is described, an AdvancedEvolved Universal Terrestrial Radio Access (E-UTRA), or LTE-Advanced(LTE-A), system which supports CA will be focused on, but the subjectmatter of the present invention is also applicable to othercommunication systems having similar technical backgrounds and channelforms in a scope which does not largely depart from the scope of thepresent invention with some modifications. Such an application may alsobe possible by determination of those of ordinary skill in the art. Forexample, the subject matter of the present invention may also be appliedto a multicarrier High Speed Packet Access (HSPA) scheme which supportsCA.

If there is data to be transmitted, the LTE rel-10 terminal receivesscheduling information for PUSCH transmission from a base stationthrough a PDCCH. The scheduling information is also called UL resourceassignment information (or a UL grant), and in the LTE rel-10, DownlinkControl Information (DCI) formats 0 and 4 are defined as the UL grant.The base station may send a request for aperiodic channel information,or an aperiodic Channel Quality Indicator (CQI), to the terminal byusing a channel information request field, or CQI request field, of theUL grant. The CQI request field is of 1 bit when CA is not supported; ifCA is supported, the CQI request field is of 2 bits. The terminal havingreceived the CQI request field of 1 bit checks the CQI request field,and upon receiving the CQI request, multiplexes the channel informationfor a serving cell in which the UL grant is transmitted with data of aPUSCH, and transmits the multiplexed channel information to the basestation. The terminal having received the CQI request field of 2 bitschecks the CQI request field, and upon receiving the CQI request,multiplexes channel information for a serving cell indicated by the CQIrequest field with data of the PUSCH and transmits the multiplexedchannel information to the base station.

Next, referring to FIG. 1, a detailed description will be made of aprocess of requesting and transmitting the aperiodic CQI when the CQIrequest field is of 1 bit and the CQI request field is of 2 bits.

FIG. 1 is a flowchart illustrating a process of requesting andtransmitting the aperiodic CQI in LTE rel-10.

In FIG. 1, a CQI request field of a different bit is set by a basestation according to whether CA is set for an LTE rel-10 terminal. If CAis set for the terminal in step 100, the base station sets a CQI requestfield of 2 bits in a UL grant in step 111. In this case, when sending achannel information request or a CQI request, the base station sets theCQI request field of 2 bits with a value desired by the base station,except for ‘00’. ‘01’ corresponds to the CQI request with respect to aserving cell in which the PUSCH is transmitted, and ‘10’ and ‘11’correspond to the CQI request with respect to a serving cell to be setin Radio Resource Control (RRC).

In step 112, the base station transmits a UL grant in which the CQIrequest is set to the terminal. In step 113, the terminal, afterreceiving the UL grant, transmits the channel information for a servingcell indicated by the CQI request field in the PUSCH. The serving cellindicated by the CQI request and the serving cell in which the PUSCH istransmitted may be the same as or different from each other.

Referring back to step 100, if CA is not set in the terminal, then thebase station sets the CQI request field of 1 bit in the UL grant andsets the CQI request field to 1 to request the channel information instep 121. In step 122, the base station transmits the UL grant in whichthe CQI request is set to the terminal. In step 123, the terminalreceives the UL grant, recognizes the CQI request, and transmits channelinformation for a serving cell in which the UL grant is transmitted inthe PUSCH. The serving cell indicated by the CQI request and the servingcell in which the PUSCH is transmitted are the same as each other. Instep 113 or 123, when the aperiodic CQI information is transmitted, itis multiplexed with data the terminal desires to transmit and istransmitted in the PUSCH. However, in the present invention, thisprocess is simply referred to as transmission of the channel informationin the PUSCH. Also in the following description, a description of themultiplexing procedure will be omitted.

In LTE Rel-10, CA is defined, and multiple serving cells may be set inthe terminal. For data scheduling of the base station, with higher-layerinformation, the terminal is set to periodically transmit channelinformation as well as to aperiodically transmit channel information asdescribed in FIG. 1.

In an embodiment of the present invention described below, an operationof periodically transmitting channel information will be referred to asperiodic channel information transmission, and periodic channelinformation is transmitted through a Physical Uplink Control Channel(PUCCH) of a primary serving cell (Pcell). For a CA-set terminal, eachserving cell independently defines periodic channel informationtransmission. Types of information to be transmitted in periodic channelinformation transmission may include a sub-band CQI; a sub-band CQI anda second Precoding Matrix Indicator (PMI); a wideband CQI and a PMI; awideband first PMI, a wideband CQI and a second PMI; a wideband CQI, afirst PMI, and a second PMI; a Rank Indicator (RI), a wideband CQI, anRI and a first PMI; and an RI and a Precoder Type Indicator (PTI).

Out of those types of information, information to be transmitted isdetermined according to a transmission mode based on higher-layerinformation, and such transmission information is set to have respectiveperiods and offsets according to the higher-layer information.

In periodic channel information transmission, if periodic channelinformation transmission time instants for multiple serving cellscoincide with each other in one sub-frame, only periodic channelinformation for only one serving cell is designed to be transmitted in aPUCCH of the Pcell in one sub-frame. In one serving cell, iftransmission time instants of multiple channel information coincide witheach other in one sub-frame, only single channel information istransmitted. In this case, the priorities of periodic channelinformation which is set to be transmitted for multiple serving cellsare determined using types of information to be transmitted and servingcell indices, such that only periodic channel information for oneserving cell is transmitted and periodic channel information for theother serving cells is discarded.

For example, if transmission time instants of multiple channelinformation for one serving cell coincide with each other, channelinformation including an RI has the highest priority; if transmissiontime instants of channel information for multiple serving cells coincidewith each other, channel information including an RI or a first PMI hasthe highest priority and channel information including a wideband CQIhas the next highest priority. If channel information having equalpriorities are transmitted for different serving cells, channelinformation having a lower serving cell index has the higher priority.Actually, in LTE rel-10, a scenario of setting of two serving cells isassumed, such that there is not much periodic channel informationtransmission collision for multiple serving cells. In addition, the basestation may differently set periodic channel information transmissionperiods and offsets for the serving cells, thereby easily avoiding suchcollisions.

However, if a scenario of setting of up to five serving cells is assumedas in LTE rel-11, it is difficult to avoid periodic channel informationtransmission collisions for the multiple serving cells merely bydifferently setting periodic channel information transmission periodsand offsets for the serving cells at the base station. As a result, theprobability of coincidence between channel information transmission timeinstants in one sub-frame is far higher than in LTE rel-10. Moreover,if, as defined in LTE rel-10, the terminal transmits single periodicchannel information only in one serving cell and periodic channelinformation for the other serving cells are discarded, then the basestation may have a difficulty in performing optimal scheduling for theother serving cells, negatively affecting the amount of datatransmission to the terminal.

If the base station transmits a UL grant including an aperiodic channelinformation request to transmit channel information for the multipleserving cells, the base station has to transmit the UL grant in eachserving cell or each time when periodic channel information transmissiontime instants for the multiple serving cells coincide with each other,wasting PDCCH transmission resources and thus reducing PDCCH resourcesfor scheduling of other terminals in the base station. Therefore, ifsetting of up to five serving cells is supported for CA in LTE rel-11, aneed exists for a method for supporting periodic channel informationtransmission for as many serving cells as possible in one sub-framewithout needing PDCCH transmission resources.

In an embodiment of the present invention described below, a descriptionwill be made of a method for transmitting channel information formultiple serving cells at a terminal, without wasting transmissionresources of a DL control channel in a wireless communication systemwhich supports CA.

The present invention is structured as described below.

A method for setting periodic channel information transmission formultiple serving cells at a base station and a method for transmittingchannel information for the serving cells at a terminal are provided,without wasting PDCCH transmission resources in a CA situation. Asolution to collisions between various UL transmission channels in thesame sub-frame will also be described with regards to an embodiment ofthe present invention.

First, a description will be made of a method for setting Uplink ControlInformation (UCI) PUSCH transmission at the base station without wastingPDCCH transmission resources, to allow the terminal to transmit periodicchannel information transmission for multiple serving cells.

A method of the present invention to prevent loss of much channelinformation due to coincidence between transmission time instants ofmultiple channel information when periodic channel information istransmitted through a PUCCH will be referred to as UCI PUSCH, which is amethod for transmitting multiple channel information through a PUSCH.

A UCI PUSCH operation mode is set by a higher-layer signal. In anembodiment of the present invention, the higher-layer signal will bedefined as UCIPUSCHmode. If UCIPUSCHmode is 0, that is, if the UCI PUSCHoperation mode is not set, the terminal performs the LTE rel-10operation of transmitting single channel information through a PUCCH inone sub-frame when transmitting periodic channel information. IfUCIPUSCHmode is 1, that is, if the UCI PUSCH operation mode is set, UCIPUSCH transmission is set in the terminal to allow the terminal totransmit a lot of channel information through the PUSCH in onesub-frame.

After the UCI PUSCH operation mode is set by the higher-layer signal,the UCI PUSCH operation of the terminal is activated as described below.First, if transmission time instants of two or more different channelinformation for one serving cell coincide with each other in onesub-frame, UCI PUSCH instead of PUCCH is activated. Next, iftransmission time instants of two or more different channel informationfor different serving cells coincide with each other in one sub-frame,UCI PUSCH instead of PUCCH is activated. The two or more channelinformation for the different serving cells may be of the same type ormay be of different types.

Once UCI PUSCH is activated, the terminal multiplexes preset channelinformation for at least one serving cell by using a preset method fortransmission in the PUSCH. The preset channel information may includechannel information corresponding to periodic channel transmissionsettings, which are set to be transmitted for the respective servingcells. As another example, the preset channel information may alsoinclude not only single channel information which may be originallytransmitted, but also channel information which may not be transmitteddue to coinciding channel information transmission time instants. Thepreset method for multiplexing the channel information multiplexes thechannel information in an order corresponding to serving cell indicesand channel information types. That is, the channel information set tobe transmitted may be first arranged according to serving cell indicesand then arranged according to channel information types. Alternatively,the channel information set to be transmitted is first arrangedaccording to channel information types and then arranged according toserving cell indices.

The multiplexed channel information are encoded at a preset encodingrate and modulated by a preset modulation scheme, and are transmitted tothe base station on a preset transmission resource through the PUSCH.The encoding rate, the modulation scheme, and the transmission resourcemay be set by a higher-layer signal similar to the UCI PUSCH operationmode setting. As another example, the encoding rate, the modulationscheme, and an initial position of a resource, that is, a start positionof an initial Physical Resource Block (PRB), are set by a higher-layersignal, and the position of the resource, that is, the start position ofthe PRB, may be differently set by a predefined hopping pattern eachtime when channel information transmission time instants coincide witheach other. As inputs of the hopping pattern, for example, an RNTI(Radio Network Temporary Identifier), a sub-frame number, and an initialposition of a resource may be set.

In addition to the start position of the PRB, a transmission resourcequantity for determining transmission resources has to be set as well.To set the transmission resource quantity, for example, the transmissionresources may be predefined based on a resource quantity which isrequired in transmission of channel information, which could not betransmitted due to coinciding transmission time instants. It is assumedthat the number of bits of channel information to be transmitted due tocoinciding transmission time instants is x and a resource quantityrequired based on a beta value, which is used to determine (adjust) anecessary resource quantity, is y PRBs. If the number of bits of channelinformation to be transmitted due to coinciding transmission timeinstants is greater than x and less than 2x, then the resource quantityis 2y PRBs. If the number of bits of channel information to betransmitted due to coinciding transmission time instants is greater than2x and less than 3x, then the resource quantity is 3y PRBs. If thenumber of bits of channel information to be transmitted due tocoinciding transmission time instants is greater than 3x and less than4x, then the resource quantity is 4y PRBs. Likewise, if the number ofbits of channel information to be transmitted due to coincidingtransmission time instants is greater than 4x and less than 5x, then theresource quantity is 5y PRBs.

As another example for setting the transmission resource quantity, thetransmission resources may be predefined as in Table 1 by consideringthe number of channel information which could not be transmitted due tocoinciding transmission time instants.

TABLE 1 Channel Information Having Number of PRBs CoincidingTransmission Time (Physical Resource Blocks) Instants (x) 1 0 < x ≦ 2 22 < x ≦ 4 3 4 < x ≦ 6 4 6 < x ≦ 8 5  8 < x ≦ 10

Next, serving cells for performing UCI PUSCH transmission will bedescribed. According to an embodiment of the present invention, theserving cell for transmission of the UCI PUSCH may be the Pcell. ThePcell is set to transmit a PUCCH, such that when collision occursbetween two or more periodic channel information transmissions, thePcell transmits the UCI PUSCH instead of the PUCCH and transmits UCI tobe transmitted in the PUCCH through the UCI PUSCH in every transmissionof the UCI PUSCH, thereby reducing PUCCH transmission power.

The serving cell for UCI PUSCH transmission may also be a Secondary cell(Scell). In this case, one Scell may be selected from among multipleScells using cell indices. For example, a Scell having the lowest cellindex may be selected. If the UCI PUSCH is transmitted in the Scell, UCItransmission from the terminal may be simply defined. For example, whendifferent TDD UL-DL configurations are applied between inter-bands ininter-band Time Division Duplexing (TDD) CA, UCI transmission timingsare different in the Scell and the Pcell, and therefore, a new terminalprocedure has to be defined when UCI for the Scell are transmitted inthe Pcell. However, if the UCI PUSCH is transmitted in the Scell, theUCI for the Scell may be transmitted on the Scell, such that it is notnecessary to define a new terminal procedure.

Referring to FIGS. 2 and 3, a description will be made of a process ofsetting UCI PUSCH transmission to transmit channel information formultiple cells at the base station and a process of transmitting the UCIPUSCH for the channel information for the multiple serving cells at theterminal according to an embodiment of the present invention.

First, the operation of the base station will be described withreference to FIG. 2. FIG. 2 is a flowchart illustrating a process ofsetting the UCI PUSCH to transmit channel information for multipleserving cells at the base station according to an embodiment of thepresent invention.

In step 201, the base station sets a higher-layer signal for an UCIPUSCH operation according to the embodiment of the present invention. Instep 202, the base station transmits the higher-layer signal to theterminal. In step 203, the base station determines whether transmissiontime instants of two or more periodic channel information coincide witheach other in one sub-frame. If so, the base station receives a UCIPUSCH transmitted from the terminal in step 204; otherwise, if thetransmission time instants of two or more periodic channel informationdo not coincide with each other, the base station terminates theprocess. After step 204, the base station may transmit a HARQ-ACK to theterminal as a feedback indicating normal reception of the UCI PUSCH.

The operation of the terminal will be described with reference to FIG.3. FIG. 3 is a flowchart illustrating a process of transmitting channelinformation for multiple serving cells at the terminal according to anembodiment of the present invention. In FIG. 3, the higher-layer signalreceived from the base station corresponds to the UCI PUSCH operationmode.

In step 301, the terminal receives the UCI PUSCH operation modeinformation from the base station. In step 302, the terminal determineswhether transmission time instants of two or more periodic channelinformation coincide with each other in one sub-frame. If so, theterminal transmits the UCI PUSCH in a preset way according to theembodiment of the present invention, in step 303. After step 303, theterminal may receive a HARQ-ACK from the base station as a feedbackindicating normal reception of the UCI PUSCH. If not, the terminalterminates the process.

Hereinafter, a description will be made of a terminal's operation uponoccurrence of collision with another UL channel transmission when theUCI PUSCH operation mode is set and the UCI PUSCH is transmitted fromthe terminal.

First, if a UCI PUSCH transmission collides with a PUCCH transmissionincluding the HARQ-ACK or the like in one sub-frame of the same servingcell, the terminal transmits UCI of the PUCCH having the collisionthrough the UCI PUSCH and does not perform PUCCH transmission. Byperforming only UCI PUSCH transmission, the terminal's power consumedfor the PUCCH transmission may be reduced. However, if HARQ-ACK bits formany cells need to be transmitted in the PUCCH, many HARQ-ACK bits haveto be included in the UCI PUSCH, causing loss of a lot of channelinformation. Therefore, in this case, the terminal may perform onlyPUCCH transmission without performing UCI PUSCH transmission.

Second, if the UCI PUSCH transmission collides with the PUSCHtransmission for general data transmission in one sub-frame of the sameserving cell, the terminal transmits UCI of the UCI PUSCH having thecollision through the PUSCH for general data transmission and does notperform UCI PUSCH transmission. The terminal performs only PUSCHtransmission for general data transmission, thereby stably transmittingthe UCI on many resources. This is because, since UCI PUSCH transmissionhas to use resources preset by the higher-layer signal, less resourcesthan the PUSCH transmission for general data transmission are assignedby the higher-layer signal to prevent a particular terminal frommonopolizing many resources.

Third, if the UCI PUSCH transmission collides with an aperiodic PUSCHtransmission in one sub-frame of the same serving cell, the terminaltransmits UCI of the UCI PUSCH having the collision through theaperiodic PUSCH and does not perform UCI PUSCH transmission. In thiscase, the terminal may perform only the aperiodic UCI PUSCHtransmission, thereby stably transmitting the UCI on many resources.

FIG. 4 is a block diagram illustrating the base station according to anembodiment of the present invention.

Referring to FIG. 4, a scheduler 400 and a controller 401 control aPDCCH generator 402 to configure a PDCCH and to transmit the PDCCH to atransmitter 403. In the present invention, a UL data channel transmittedfrom the terminal using a UCI PUSCH is received through a receiver 404and periodic UCI information is separated by a demultiplexer 405. Theperiodic UCI information is decoded by a UCI decoder 406. If theperiodic UCI information is multiplexed in a general UL data channel,the UL data channel transmitted from the terminal is received throughthe receiver 404 and UL data information and periodic UCI informationare separated through the demultiplexer 405, such that the periodic UCIinformation is decoded by the UCI decoder 406 and the UL datainformation is decoded by a PUSCH decoder 407.

In particular, the controller 401 according to an embodiment of thepresent invention controls the operation of setting the UCI PUSCHoperation mode to allow the terminal to transmit channel information forat least one serving cell to the base station, and the operation oftransmitting the UCI PUSCH operation mode information to the terminal.

FIG. 5 is a block diagram of the terminal according to an embodiment ofthe present invention.

Referring to FIG. 5, a signal received through a receiver 500 isreceived by a PDCCH decoder 501, and channel information according tothe present invention is generated by a UCI encoder 502. Periodic UCIinformation are multiplexed in a UL data channel and transmitted to atransmitter 505 by a multiplexer 504 according to the present invention.If the periodic UCI information needs to be multiplexed in a general ULdata channel, the channel information according to the present inventionis generated by the UCI encoder 502, and UL data is generated by a PUSCHencoder 503. The periodic UCI information and the UL data aremultiplexed in a UL data channel and transmitted to the transmitter 505by the multiplexer 504.

While not illustrated in FIG. 5, the terminal may include a controllerfor receiving the UCI PUSCH operation mode information transmitted fromthe base station and transmitting channel information for at least oneserving cell to the base station through the UCI PUSCH, if transmissiontime instants of two or more channel information coincide with eachother in UCI PUSCH setting.

FIG. 6 is a flowchart illustrating a method according to the presentinvention. In step 610, information related to a period and an offset onchannel status information for each of multiple cells is identified. Instep 620, if (a) a UE is configured with more than one cell, (b) acollision occurs between the channel status information for the multiplecells, and (c) the channel status information for the multiple cells area same priority, the channel status information for the multiple cellsis transmitted on a sub-frame based on the identified information.

According to the present invention, by using a method for preventingtransmission resources for a PDCCH from being wasted in a wirelesscommunication system which supports CA, the terminal can transmitchannel information for multiple serving cells. The base stationreceives the channel information for the multiple serving cells from theterminal and performs optimal scheduling for the serving cells based onthe received channel information for the multiple serving cells, therebyimproving the transmission quantity.

While the embodiments of the present invention have been described indetail with reference to the accompanying drawings, the presentinvention is not limited thereto. It will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present invention asdefined by the appended claims.

What is claimed is:
 1. A method for transmitting channel information,the method comprising: identifying information related to a period andan offset on channel status information for each of multiple servingcells; and transmitting the channel status information for the multipleserving cells on a sub-frame based on the identified information, if (a)a UE is configured with more than one cell, (b) a collision occursbetween the channel status information for the multiple serving cells,and (c) the channel status information for the multiple serving cellsare a same priority.
 2. The method of claim 1, wherein the channelstatus information for each of the multiple serving cells is transmittedon a Physical Uplink Shared Channel (PUSCH).
 3. The method of claim 2,further comprising receiving resource information comprising at leastone of information about a transmission resource quantity for the PUSCHand information about a resource block for the PUSCH.
 4. The method ofclaim 1, further comprising receiving information indicating thatmultiple periodic channel information can be transmitted on onesub-frame.
 5. The method of claim 4, further comprising transmittingchannel status information from among the channel status information foreach of multiple serving cells, if the information indicating multipleperiodic channel information can be transmitted on one sub-frame is notreceived.
 6. A method for receiving channel information, the methodcomprising: transmitting information related to a period and an offseton channel status information for each of multiple serving cells; andreceiving the channel status information for the multiple serving cellson a sub-frame based on the transmitted information, if (a) a UE isconfigured with more than one cell, (b) a collision occurs between thechannel status information for the multiple serving cells, and (c) thechannel status information for the multiple serving cells are a samepriority.
 7. The method of claim 6, wherein the channel statusinformation for each of the multiple serving cells is transmitted on aPhysical Uplink Shared Channel (PUSCH).
 8. The method of claim 7,further comprising transmitting resource information comprising at leastone of information about a transmission resource quantity for the PUSCHand information about a resource block for the PUSCH.
 9. The method ofclaim 6, wherein transmitting information related to the period and theoffset indicates that multiple periodic channel information can betransmitted on one sub-frame.
 10. The method of claim 9, furthercomprising receiving channel status information from among the channelstatus information for each of multiple serving cells, if theinformation indicating multiple periodic channel information can betransmitted on one sub-frame is not received.
 11. An apparatus fortransmitting channel information, the apparatus comprising: a controllerfor identifying information related to a period and an offset on channelstatus information for each of multiple serving cells; and a transmitterfor transmitting the channel status information for the multiple servingcells on a sub-frame based on the identified information, if (a) a UE isconfigured with more than one cell, (b) a collision occurs between thechannel status information for the multiple serving cells, and (c) thechannel status information for the multiple serving cells are a samepriority.
 12. The apparatus of claim 11, wherein the channel statusinformation for each of the multiple serving cells is transmitted on aPhysical Uplink Shared Channel (PUSCH).
 13. The apparatus of claim 12,further comprising a receiver for receiving resource informationcomprising at least one of information about a transmission resourcequantity for the PUSCH and information about a resource block for thePUSCH.
 14. The apparatus of claim 11, further comprising a receiver forreceiving information indicating that multiple periodic channelinformation can be transmitted on one sub-frame.
 15. The apparatus ofclaim 14, wherein the transmitter transmits channel status informationfrom among the channel status information for each of multiple servingcells, if the information indicating multiple periodic channelinformation can be transmitted on one sub-frame is not received.
 16. Anapparatus for receiving channel information, the method comprising: atransmitter for transmitting information related to a period and anoffset on channel status information for each of multiple serving cells;and a receiver for receiving the channel status information for themultiple serving cells on a sub-frame based on the transmittedinformation, if (a) a UE is configured with more than one cell, (b) acollision occurs between the channel status information for the multipleserving cells, and (c) the channel status information for the multipleserving cells are a same priority.
 17. The apparatus of claim 16,wherein the channel status information for each of the multiple servingcells is transmitted on a Physical Uplink Shared Channel (PUSCH). 18.The apparatus of claim 17, wherein the transmitter transmits resourceinformation comprising at least one of information about a transmissionresource quantity for the PUSCH and information about a resource blockfor the PUSCH.
 19. The apparatus of claim 16, wherein the informationrelated to the period and the offset indicates that multiple periodicchannel information can be transmitted on one sub-frame.
 20. Theapparatus of claim 19, wherein the receiver receives channel statusinformation among the channel status information for each of multipleserving cells, if the information indicating multiple periodic channelinformation can be transmitted on one sub-frame is not received.